The present disclosure relates generally to a method for inspecting generator field teeth, and particularly to a method for inspecting generator field teeth for the detection, characterization and/or sizing of cracks thereat.
Typical generators used to produce electrical power employ rotor shafts having field teeth and wedges for retaining the field conductors. Typical field teeth and wedge designs employ a plurality of wedges that are arranged in a butt joint fashion along the length of an adjacent tooth, and dovetail engagement surfaces that serve to constrain the wedges during rotation of the rotor. During operation, movement of the wedges causes relative movement across the butt joint of two adjacent wedges, which in turn may cause fretting on the load surface of the tooth that is serving to constrain outward radial movement of the wedges. Fretting on the load surfaces at the butt joint between wedges can cause crack initiation at this location.
Accordingly, there is a need in the art for a method of inspecting generator field teeth for the detection, characterization and/or sizing of cracks that may occur at fretted load surfaces in an efficient and economical manner.